Hensarling next served as a vice president at two companies before becoming owner of San Jacinto Ventures in 1996 and CEO of Family Support Assurance Corporation in 2001.[citation needed] He served as vice president of Green Mountain Energy from 1999 to 2001.[citation needed]

Hensarling was elected to his first term in 2002, defeating Democratic opponent Ron Chapman with 58 percent of the vote.[citation needed] He was reelected in 2004 with 64 percent of the vote over Democratic challenger Bill Bernstein.[citation needed]

A December 31, 2005 article in National Review profiled his work as the country's "budget nanny", saying that he has replaced his mentor, former Senator Phil Gramm, in this role. Hensarling's proposed legislation is said to intend to force Congress to "decide how much money they can afford to spend, and then prioritize within those limits." The article says that "the chief problem with any proposal to reform the budget process is that it excites almost nobody."[citation needed]

In January 2008, Hensarling was co-author of the Economic Growth Act of 2008.[citation needed]

In May 2008, Hensarling campaigned for the Republican party leadership in the House to agree to a special session to give lawmakers to air their views on a new policy platform and share ideas on how to define themselves to better advantage going into the 2008 election.[citation needed]

On January 29, 2010, during President Barack Obama's meeting with House Republicans, Hensarling challenged Obama's position on the budget, asserting that the Obama White House was increasing the national deficit at the same rate per month that the previous President had increased it per year. President Obama responded with the following: "the whole question was structured as a talking point for running a campaign....[t]he fact of the matter is that when we came into office, the deficit was $1.3 trillion. So when you say that suddenly I've got a monthly budget that is higher than the annual – or a monthly deficit that's higher than the annual deficit left by Republicans, that's factually just not true, and you know it's not true."[11] The Congressional Budget Office issued a projection in January 2009, before Obama took office, that the budget deficit would reach $1.2 trillion that year.[12]

In September 2008, Hensarling led House Republican efforts to oppose Secretary Henry Paulson and Chairman Ben Bernanke's $700 billion financial bailout, and urged caution before Congress rushed to approve the plan. After voting against the bill, Hensarling said,

no one truly knows if this plan will work – though we all hope that it does. No one knows the true amount of taxpayer exposure. Treasury could spend $700 billion in no time flat and come right back to Congress for $700 billion more. Some believe the taxpayer will actually make money in the deal and I hope that proves true. But history as a guide, I have strong fears it will not. At what point do we finally bailout the American taxpayer from the unconscionable burden he or she faces from out of control Washington spending? I fear that the legislation passed by Congress remains more of a bailout than a work out. I fear it undermines the ethic of personal responsibility. I fear that it rewards bad behavior and punishes good. But my greatest fear is that it changes the role of the federal government in our free market economy, which despite its current problems, remains the envy of the world. How can we have capitalism on the way up and socialism on the way down? If we lose our ability to fail will we not in turn lose our ability to succeed? If Congress bails out some firms and sectors, how can it say no to others? We must always be very careful to ensure that any remedy does allow short-term gain to come at the cost of even greater long-term pain – that being the slippery slope to socialism. The thought of my children growing up in America with less freedom and less opportunity is a long-term pain I cannot bear.